Telephone-exchange system



Aug.. M2 lmg E. H. MLLLS TELEPHONE EXCHANGE SYSTEM Filed Sept. 25 1920 Patented Ang. l2, i924..

ELLIS I-I. lVILLS, OF EAST ORANGE, NEW' JERSEY, ASSIGNOR TO WESTERN ELECTRIC COMPANY, NCOR-FORATED, OF NEV YORK, N.

Y., A CORPORATQN OF NEW' YCRK.

TELEPHONE-EXCHANGE SYSTEM.

Application filed September 25, 1920.

To all whom t may conce/m:

Be it known that l, Eems H. Mums, a citizen of the United States of America, residing at East Orange, in the county of Essex, State of N ew Jersey, have invented certain new and useful Improvements in rTelephone-EXchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to a telephone exchange system and more particularly to a system in which the prepayment or registration of a toll is necessary before the desired connection can be fully established.

In systems of this character it is customary to provide the substation of a subscribcrs line with a coin box and to effect the establishment of a desired connection by the deposit of a coin of the proper denomination in the coin box. rlhe coin box is provided with a magnet for causing the refunding or collection of the coin and with contact means operated by the deposit of the coin for connecting the magnet from one concluetor of the subscriber-s line to ground. Unscrupulous subscribers sometimes seek to evade payment by simulating the deposit of a coin through the connection of a ground to the line, independently of the coin box. It is, therefore, an object of this invention to provide means for l'neventing a subscriber from obtaining a desired connect-ion except through the actual deposit of a coin in the coin boX.

It is a further object of the invention to apply means for detecting a fraudulent operation of a subscribes toll device to an automatic telephone system in such a manner that the calling subscriber may establish a desired connection to substantially its tinal switching stage before being required to deposit a coin.

A feature of the present invention resides in the employment of means for preventing the completion of a desired connect-ion until after the deposit of the required coin, and further means comprising two marginal differential relays which, when operated by the proper deposit of a coin, render the preventing means ineffective and which, when operated in a different manner by an attempt to simulate the deposit of a coin, have no effect upon the preventing n'ieans.

A further feature of the invention resides in the employment of means as speciiically Serial No. 412,717.

applied to a telephone sys-tem in which connections are established by automatic switching devices for preventing the establishment of a connectibn from progressing beyond a specified switching stage until after the actual deposit of the required coin in the coin box of the calling line. ln systems of this character it is often desirable to permit a subscriber to entirely dial a desired number and to thereby initiate the selective operations at the central oiiice before requiring him to deposit a coin, in order that. thecentral station apparatus, after having been seized by the calling subscriber, may proceed without delay to extend the. connection towards the desired line.

@ther features of the invention will'be apparent as the description of the invention progresses. The invention will now be described in connection with the accompanying drawings in which- F ig. l illustrates the invention as applied to a system in which connections are established by automatic switching devices; and

F ig. 2 illustrates the invention as applied to a system in which connections are established through the medium of an operators manual circuit.

In Fig. l the switching devices have been diagrammatically represented by their respective switch brushes, and the central otliee switch controlling register-sender by the apparatus disclosed within the dotted rectangle, it being considered unnecessary to complete understanding of this invention to disclose in full the operating mechanism and circuits of the switches and the mechanism of the register-sender. The switches and sender may be of the type disclosed in the Patent No. 1,395,977, issued November l, 1921, to F. A. Stearn and F. J. Scudder, and may function in the establishment of a connection in substantially the same manner as described therein. The sequence switch cams, associated with the district selector switch QO, are controlled by a sequence switch (not shown) associated therewith in the well-known manner. The equence switch cams shown in the rectangle are controlled by a sequence switch (not shown) associated with the register-sender.

The invention will first be described in connection with the disclosure of Fig. l, it being assnn'ied that the calling subscriber A desires to establish a connection with the line .Y Aupper contact et sequence switch cani 1&3,

and the lower contact ot sequence switch cani 14, to conductors 15 and 1G respectively, extending to the register-sending n'i'echanisni shown within the dotted rectangle through the normal contacts ot relay 33.

ln'response to the operation of the impulse dial S, the'registers of the registersend'er are set in the well-known manner to register the code representing' the ollice designationof the desired line and the number of the line in the desired oilice, and the sender then proceeds to set the district selector 20, the incoming selector 30, and the final selector l0 to extend the connection from trunk conductors 11 and 12 to the terminal of the desired line. The incoming selector 30 and the final selector d() are controlled in the well-known manner over the fundamental circuit, which may he traced from trunk conductor 17, terminal 1S and brush 19 of the district selector 20, conductor 21, the right-hand contacts ot sequence switch carni 22, conductor 23, the armature and hack contact et O countingg` relay 24C, the .windings ot the sender stepping relay 25, the armature and hack contact of relay 26, the right-hand contacts ot sequence switch cam 27, trunli conductor 2S, brush 29 and terminal 31 ot the district selector 20, and thence to the trunk conductor 32. ln the well-known manner, under the control ot the registers of the sender and the counting,` relays, the incoming selector 30 isv adjusted in its brush selection and Igroup selection movements with the sequence switch of the sender in positions G and 8 respectively, and following the selective morements ot the incoming selector switch the fundamental circuit is further extended to an idle linal selector switch 40, which final selector switch is controlled in its brush selection and tens selection movements with the sequence switch ot the sender in positions 1() and 12 respectively.

Following,` the completion of the tens selection movement ot the final selector switch 40, the sequence switch of the sender advances out of position. 12 and into position 14. It at this time the calling subscriber has not rdeposited a coin in the coin hox ot his substation, a circuit is established 'tor relay 26, which may he traced 'from grounded battery through the winding` ot relay 26, the contact otl sequence switch cam 3l, (i3 to 1i) and thence to ground through the armature and hack contact of the dilerential marginal relay llelay 26, upon energizing, opens the fundamental circuit previously traced at its :nniature and hack contact and therefore prevents the control ot the linal selector switch 1n its units .selection movement, and the extension ot the connection is, there/tore, arrested at this point o't its iin'ogfjress until the suhsciiher has eithr deposited the required coin o' aliandons the call.

it the calling` suhscrihcr has deposited the required coin prior vto the advance ot the sequence switch ot the sender into position 13, then the dilleimntial marginal relay 35 is energized, thereby openinfi` the circuit ot relay 2G., so that when the sender sequence switch reaches position 1i, the YIuinhuncntal circuit, extending to the final selector switch, is closed and theretore ellectirc 'tor controlling the setting` ot the linal selector switch upon the terminals oit the desired line. The circuit 'ior relay 3.3 inay he traced i'roni grounded liattery through the righthand windinc ot relay 35, the right-hand winding` ot di'tlierential marginal rela)7 llo, the outer armature and front contact ot relay 33, which is energized l'illowing;- the completion of registration ot the all at the sender, conductor l5, the upper contact ot sequence s vitch cam 1?), conductor 11, the upper hanhV terminal and brush ot' line switch 10, the windingl ot the coin box inap;- net 237, which is o't approxiinately 1000 ohins resistance and thence to `:ground througrh contacts 3S. wnich were permitted to close when the calling' snhecriher deposited the coin. rllhe curreiit llowing in this circuit. while snliicient to energize relay 35, is not sullicient to enc srixe relay riG, and therefore the circuit prin iously traced tor relay 2G is opened at they arinaturi and hack contact ot re1 i Relays 8.7 and 3G, heine' ditl'crentially wound, do not energize in the series rircuit, which may he traced from grounded battery through the right-hand windings oi these relay-e, the outer armature and iti-ont Contact of rela).7 323, conductor l5 the upper contact o't sequence switch cani 13, thence over the suhscrihefs line and hack through the lower contact ot sequence switch cani l-ft. conductor 15 the inner armature and trout contact ot' rela;T S3 and to lground through the lett-hand windings ot relay 3G and f1.3.

lit the calling;` suhscriher attempts to simu-- late the deposit ot a coin hy directly grounding the tip conductor ot his line at the ,suhstatitni` independently o't the ground torougjh the winding' ot the coin hoi; niaginct then snilicicnt curi-cnt Hows through the i--hand windings ol'V relays in and il?) lo hotli o' these relays.

Relay 23.3,

upon energizing, opens the circuit of relay 26, but since at this time relay 36 is also energized, the circuit or' relay 26 is eiectively closed at the armature and front contact of relay 36 when the sender sequence switch closes the contact of cam 34C upon reaching position 13, and thus the progress of the connection is arrested immediately prior to units selection, in the same manner as when the calling subscriber failed to deposit the required coin.

0n party lines the bells at the subscribers stations are customarily connected, some to the tip cnnductor ol the line, and others to they ring conductor of the line, through the normally close-d contacts of the switchhooks at the several stations. The grounded bell conductor therefore extends to the desk set through the extension cord together With the tip and ring talking conductors. Should a subscriber endeavor to simulate the deposit of a coin by puncturing the extension cord with apin or other sharp instrument for the purpose of connecting the bell ground to either the tip or ring conductor, then owing' to the high resistance of the bell ground Which is approximately 4000 ohms, insufficient current flows through the windings of relays 36 and 35 to energize them since relay 36 is designed to energize only upon the connection of a direct ground at. the subscribers substation,- and -relay 35 is designed to operate only When the resistance of its external circuit is lessi than 3800 ohms. Since neither relay 35 nor 36 is energized the same condition prevails as When the subscriber deposits no coin, and the progress of the call is arrested.

Following the successful extension of the connection to the terminals of the desired line B, the sequence switch of the district selector 2O is advanced out ot' position l0, in the Well-known manner, and into position l-l, in which position the calling subscribers line A is 4connected for conversation with the subscribers line B. Talking current is supplied to the subscribers lines, in the well-known manner, and the collection of the coin` deposited in the coin box of the calling line is made in the usual manner by the energization of magnet- 37 uplon the termination of the conversation after the calling subscriber has restored hisI receiver to the sivitchho'ok. F or coin collection circuits funct-ioning in, this manner, reference may be had to Patent 1,332,222, issued lllarch 2, 1920, to A. E. Lundell and George Thompson.

In Fig. 2 the invention has been disclosed in connection with manual circuits. lt will be assumed that `the subscriber at substation C desires to obtain a connection with a subscriber at lsubstation D, and to initiate the call removes his receiver from, the switchhook. Upon the removal of the receiver from the sWitchhook a circuit is established for the line relay 67, which may be traced from grounded battery thro-ugh the righthand Winding of relay 67, the right-hand armature and` back contact o'l cutoit` relay 68, thence over the subscribers line loop, and back through the left-hand armature and back contact ot' relay 68 to ground through the left-hand Winding of line relay 67. .Relay 67, energizing in this circuit, establishes a circuit for the line lamp 39.

The operator, upon noting the illumination of the line lamp 39, picks up the answering plug P of an idle cord circuit O at her position and inserts iit in, the jack J of the calling line. A circuit is now established from battery through the coin test lamp 4l, the normally closed make-beforebreak contacts of the inner lett-hand armature of relay 42, the sleeve contact i3 of the plug P, the sleeve contact 44 of the jack J, and thence to ground lthrough the Winding' of cutoff relay 68. Lamp al is illuminated in this circuit and. relay 68 energizes. The energization of relay 68 ope-ns, at its armatures and back cont-acts, the circuit previously traced for line relay 67, thereby extinguishing the line lamp 39.

The operator noiv depresses the listening key l5 to connect her head set indicated at OT to the subscribers line over the contacts yof the keys 55' and 56 and the tip and ring contacts of the plug P and jack J, and obtains from the calling subscriber the number of the line desired. ln response to the instructions received from the cfa-lling subscriber, the operator then tests the multiple terminal of the desired line in the usual manner to determine its free or busy condition, and if found free inserts the calling plug P of the cord circuit O in the jack J of the desired line D.

Upon the insertion of the plug P in the jack J, a circuit is established -trom grounded battery through the supervisory lamp 46, the sleeve contact 47 of the plug P', sleeve contact1 4S of jack J, and thence to ground through the cutoff` relay t9 of the desired line. The lamp 46 becomes illuminated and remains illuminated until the called subscriber responds toz the application of ringing current, which the operator applies to the called line in the Well-known manner. Vhen the called subscriber responds, the supervisory relay 5() becomes energized over the called subscribers line loop in the Wellknown manner, closing, at its armature and front contact, a shunt around the supervisory signal lamp 46 elfacing the signal.

Upon the successful extension of the connection to the desired line, the operator again depresses the listening key 4 5 and instructs the calling subscriber to deposit the required coin. The operator then releases the key 45. When the calling subscriber in response to the instructions of the operator deposits the required coin in the coin box, the contacts 51 at the coin boX are closed to connect the windings of the coin box magnet 52 from ground to the tip conductor of the calling sub-scribers line. A circuit is now established from grounded battery through the right-hand winding ofthe differential marginal relay 53, the right-hand winding of the differential marginal relay 54, the right-hand armature and back contact of relay 42, the upper normally closed contact of listening-in key 45, the upper normally closed icontact of the coin collect key 55, the upper normally closed contact of the coin refunding key 56, the tip contacts of plug l) and jack J, the tip conductor of the calling subscribers line, and thence to ground through the windings of magnet 52 and contacts 51. Due to the resistance of the coin box magnet 52, marginal relay 54 does not energize in this circuit. Marginal relay 53 becomes energized. A circuitV is therefore established for relay 42, which may be .traced from grounded batt-ery through the right-hand winding of relay 42, the armature and back contact of relay 54, and thence to ground through the armature and front con-tact of relay 53. Relay 42, vupon energizing, closes a locking circuit for itself which may be trace-d from grounded battery through the winding of supervisory signal lamp 57, conductor 58, `the left-hand winding of relay 42, the make contacts of the. inner left-hand armature of relay 42, sleeve contact 43 of the plug` l), sleeve contact 44 of the jack J, and thence to ground through the winding of cutoff relay 68. back contact and outer left-hand armature and back contact, relay 42 opens the circuit extending through the windings of relays 53 and 54', and at the front contact-s of these armatures extends the tipand ring conductors of the answering end of the cord circuit from the plug l) to the left-hand windings of the repeating coil 59. At its inner left-hand armature relay 42 opens the circuit'previously traced through the coin test lamp 41, thereby extinguishing the lamp to signify yto the operator that a coin has been deposited in the proper manner. Supervisory signa-l lamp 57 does not Ibecome illuminated in the circuit previously traced through the left-hand winding of relayr42, since upon the energization of relay 42 and the connection of the answering strands of the cord circuit to the left-hand windings of repeating coil 59, the answering supervisory relay 60 become-s energized over the calling subscribers line loop, and at its left.- hand armature and front contact closes a shunt around the supervisory signal lamp` 5T.

Due to the fact that relays 53 and 54 are At its right-hand armature and.

differentially wound, these relays do not become energized when connected through the right-hand arma-ture and back contact and outer left-hand armature and back contact of relay 42, and thence over the calling subscriber-s line loop, but energize only when a. ground is connected to the tip conductor of the calling line. Following the termination of the conversation between subscriber C and subscriber Vl), the subscribers restore their receivers to their switchhooks, thereby opening the circuits of supervisory relays (30 and 5t), causing the illumination of supervisory signal lamps 57 and 4G in `the well-known manner. The opeator then. proceeds to take down the connection, whereupon all apparatus employed in the establishment of the connection is restored to normal condition.

lf the calling subscriber, through Athe fraudulent connection of a direct ground to the tip conductor of his line, attempts to obtain a completed connection without the proper deposit of a coin in the coin box, his act is defeated in the following manner: Upon the connection. of the direct ground to the tip coiuluctor of the calling line, a circuit is established from grounded battery through the right-hand windings of relays 53 and 54, the right-hand armature and back cont-act of relay 42, and thence as previously traced over the tip conductor of the calling line and to ground directly through the fraudulent ground connection. Since the ground connection is of much lower resistance than the f connection through the windings of the coin box magnet 52, both marginal relays 58 and 54 now become energized, and although relay 53 attracts its armature to establish a connection through the right-hand winding of relay 42, relay 54 breaks this established connection at its armature and back contact and therefore relay 42 does not energize, and therefore the coin Ltest lamp 4l. remains illuminated to signify to the. operator that the calling subscriber has not yet deposited the required coin. Since relay l2 is not cnergizcd, the talking circuit bet weon the ralling subscribei"s line and the called `subscribers line remains open at the contacts of this relay.

lf the operator desires to give the calling subscriber a free connection to the line, desired. the operator depresses the coin refunding key 56, which, at its lowermost Contact, closes a circuit from grounded battery through the right-hand winding of relay 42, thence over conductor (3l to ground at the contact of key Relay 42 becomes energized and, in the manner previously described, causes the closure of the tip and ring coiuluctors of the cord circuit., thereby permitting communication between the ralling and called subscribers. lf at any time prior to the energization ot relay l2 the operator wishes to converse with the called subscriber, the operator depresses hey 62, which connects her head set to the calling strands of the cord circuit and thereby to the called subscribers line.

While the invention has been disclosed in both modilications as employed with subscribers lines having coin boxes, it is to be understood that the invention is equally applicable 'for use with subscribers7 lines provided with toll charging apparatus, as, for example, message registration apparatus.

lli/That is claimed is:

l. ln a telephone exchange system, a central otlice, a calling line, a called line, means at said central otlice for extending a connection between said lines, a charging device on said calling line, means at said c:=n tral cnice for arresting the completion ot said connection until after the operation orn said charging device, and means comprising a plurality of marginal differential relays tor rendering said arresting means ine-ticetive.

2. ln a telephone exchange system, a central otiice, a calling line, a called line, means at said central oihce tor extending a connection between said lilies, a charging device on said calling line, a relay at said central oiice for arresting the completion otsaid connection until after the operation ot said charging device, and means comprising a plurality of marginal dierential relays under the control oit said charging device for controlling said first relay to etiect the completion of said connection.

3. ln a telephone exchange system, a central silice, a calling line, a called line, means at said central oiiice tor extending a connection between said lines, a toll device on said calling line, a relay at said central ot- ;Vice ior arresting the completion of said connection until after the operation of said toll device, a pair oi' marginal differential relays under the control ot said calling line, and a circuit for said tiret relay extending through contacts or' said latter relays for effecting the operation of said first relay to complete said connection upon the proper operation of said toll device.

Il. ln a telephone exchange system, a een tral otllce, a calling line, a called line, means at said central otlice for extending a connection between said lines, a toll device ron said calling line, a. relay at said central otiic-e for arresting the completion of said connection until alter the opeation of said toll device, a pair ot marginal differential relays under the control of said calling line, and a circuit for said first relay extending through contacts oi said latter relays, said circuit being rendered eliect-ive to control said lirst relay to complete said connection upon the operation of one ot said latter r-elays when said toll device is properly operated and rendered ineffective upon the operation ot the other ot said relays upon an attempt to simulate the operation of said toll device.

5.V ln a telephone exchange system, a central ottico, Va calling line, a called line, means at said central oiiice tor extending a connection between said lines, a toll device on said calling line, a relay at said central oiiice for arresting the completion ot said connection untilat'ter the operation of said toll device, a pair of marginal dierential relays under the control otsaid calling line, and a circuit for said lirst relay extending through contacts oit said latter relays, said circuit being rendered effective to control said first relay to complete said connection upon the operation ot one of said latter relays when said toll device is properly operated and rendered ineffective upon failure of said latter relays to operate upon an attempt to simulate the operation ot said toll device by the connectiony of a high resistance ground to either of the conductors ot saidL calling line. n

6. In a telephone exchange system, a cen tral otiice, a calling line, a called line, means at said central olilce for extending a connection between said lines, a coin collecting device on said calling line, a relay at said central oilice for arresting the completion of said connection until after the operation of said device, a pair of marginal (liderential relays under the control of said calling line, both of said relays being responsive to a direct ground connection upon one conductor ot said calling line and one only of said relays being responsive to a high resistance ground connection on said conductor, and a circuit for said lirst relay eX- tending through contacts of said latter relays, said Vcircuit being rendered eiiective to control said relay to complete said connection upon the connection ot a resistance ground to said conductor through the deposit oi' a coin in said coin device and rendered ineffective upon the connection of a direct ground to said conductor upon an attempt to simulate the deposit of a coin.

7. ln a telephone exchange system, a call` ing line, a called line, selector switches for extending a connection between said lines, a charging device on said calling line, means tor arresting the operation of one ot said switches to complete said connection until after the operation of said charging device, and means comprising a plurality of marginal relays for rendering said arresting means ineilective.

8. ln a telephone exchange system, a calling line, a called line, selector switches comprising a final selector switch having access to the terminal of said called line for eX- tending a ,connection between said lines, a

charging device on said calling line, means or arresting the operation ot said linal selector switch until after the operation of said charging device, and means comprising fa plurality of marginal dinierentialrelays l' torrende'ring said arresting means inetllective.`

" 9. ln a telephone exchange system, a call- ],ing`line, a called line, selector switches operable' in a plurality of Aswitching stages to extend a connection between said lines` a charging devicel on said calling line, means Y for arresting the progress of said connection Yso a lsending mechanism lior controlling said switches, a chargingdevice on said calling line, means for a 'resting the operation ol .said sending mechanism in'nnediately prior to the control ot saidswitches in the last of' said switching stages and until after the operation ot saidrcharging device, and means controlled by the operation of said device 'for rendering said arresting means ineliective. n

"11. ln a telephone exchange system, a calling line, a called line, selector switches Voperable in a plurality of switching stages to extend a connection between said lines, a sending mechanism, a control circuit extending between said mechanism and said switches, a charging device on said calling line, means for opening said control circuit immediately prior to the operation of said sending mechanism for controlling said selector switches in the lastV of said switching stages and until after the operation of said charging device, and means controlled bythe operation of said device for rendering said arresting means inei'i'ective.

12. ln aV telephone exchange system, a calling line, a called line, selector switches operable in a plurality ot' switching stages to extend a connection ,between said lines, a sending mechanism, a control circuit ex-l tending between said mechanism and said switches, acharging device on said calling line, a relay for opening said controlcircuit f immediately prior to theV operation of said yso sending mechanism for controlling said selector switches in the last of said snf'itching` stages and until alterV the operation ol' said charging device, and a plurality of marginal 4differentialrelays under the control of said calling line for controlling said relay.

18. ln a telephone exchange system, a calling line, a called line, selector switches operable in a plurality ot switching stages to extend a connection between said lines, a sending mechanism, a control circuit extending between said mechanism and said switches, a toll device on said calling line, a relay for opening said control circuit immediately prior to the operation ot said sending mechanism for controlling said sclector switches in the last olE said switching stages and until alter the operation ot said toll device, a pair ol' marginal dill'erential relays under the control olf said calling line, and a circuit for said first relay extending through contacts of said latter relays, said circuit being rendered inel'l'cctive to operate said lirst relay7 upon the operation ot one ot said latter relays when said toll device is properly operated and rendered etl'cctive to operate said relay upon the opciatioii of the other of said relays upon an attempt to simiilate the operation oit' said toll device.

14. ln a telephone exchange system, a calling line, a called line, numerical selector switches operable in a plurality ot switching stages to extend a connection between said lines, a charging device on said calling line, means for arresting the progress of .sa-id connection through said switching stages subsequent to the establishment ot said connection through certain ol said stages and prior to its establishment through all of said stages and until alter the operation of said charging device, and means controlled by the operation ot said device for rendering said arresting means ineffective whereby said arrested connection becomes completed.

15. ln a telephone exchange system, a calling line, a called line, selector switches operable in a plurality ot switching stages to extend a connection between said lines, a sending mechanism for controlling said switches, a charging device on said calling line, means lor arresting the operation ot said sending mechanism subsequent to the establishment of said selection through certain of said stages and prior to its establishment through all ot said stages and until alter the operation ot' said charging device, and means controlled by the operation of said device for rendering said arresting means iiiellective whereby said arrested con.- nection becomes completed.

16. ln a telephone system, a siibscribers line extending to a central oi'iice, coin collecting mechanism at the station on said line, automatic selector mechanism at the exchange controllable from said station only after a coin has been deposited in said coin mechanism, means at said exchange responsive to the deposit of a coin `for rendering said selector mechanism controllable, and other selector mechanism at the exchange controllable fiom said station Without deafter the operation of seid charging device, positing a coin. and means comprising a plurality of mzu- 10 17. In a telephone exchange system, e ginal dilferential relays for rendering Said central oce, a calling line, a called line, arresting means ineffective.

5 means at said central. oiiice for extending a In Witness whereof, I hereunto subscribe connection between said lines, echargng' demy name this 22nd day of September A. D., Vice on said calling line, means for arrest- 1920. ing the completion of said connection until ELLIS I'I. MILLS. 

